The conference of our European Institute for social security was held from the 16th till the 19th of October 1980 in Peruggia. As usual the theme of the Conference was the same of that of the preparatory Colloque held in Brussels in 1979: Social security reforms in Europe. The reports of that Colloque were published as Part I I of the Yearbook 1978-1980. Part I of the Yearbook 1980-1981 contains the reports presented in Peruggia. The reports are focussed on three items: The financing of social security (J.P. Launay, Jan B.M. Pierik, Jørn Henrik Petersen and Guy Perrin); The social benefits (Bernd Schulte and Sven Guldburg) and The organization of social security (A.J. Ogus, A. Berenstein and Jef van Langendonck) . The Yearbook contains also two national reports (M. Magrez and Asbj~rn Kjønstad), not available to be included in Yearbook I I 1978-1980. Finally the Yearbook contains a report from Guy Perrin on the social security problems of migrant workers and the synthesis report of Pasquale Sandulli. It's a pity that we could not include the report of Lucia Vitali, Le prestazini per inval idita nel sistema ital iano di sicurezza sociale: un anal isi economica, and the report of the Region of Umbria since there was no English or French translation available. The Institute once again wants to express its sincere gratitude to Pasquale Sandull i and his collegues for the adequate way in which they organized the conference.